drd/tests/annotate_sem.c

   1 /**
   2  * @file  annotate_sem.c
   3  *
   4  * @brief Multithreaded test program that triggers various access patterns
   5  *        without triggering any race conditions using a binary semaphore
   6  *        implemented via busy-waiting. Annotations are used to tell DRD
   7  *        which higher-level semaphore operations are being performed.
   8  */
   9
  10 #include <assert.h>
  11 #include <pthread.h>
  12 #include <stdio.h>
  13 #include "../../config.h"
  14 #include "../../drd/drd.h"
  15
  16 #define THREADS 10
  17 #define ITERATIONS 1000
  18
  19 typedef struct {
  20   volatile unsigned value;
  21 } sem_t;
  22
  23 static sem_t s_sem;
  24 static unsigned int s_counter;
  25
  26 static void sem_init(sem_t *p, unsigned value)
  27 {
  28   DRD_IGNORE_VAR(*p);
  29   p->value = value;
  30   ANNOTATE_SEM_INIT_PRE(p, value);
  31 }
  32
  33 static void sem_destroy(sem_t *p)
  34 {
  35   ANNOTATE_SEM_DESTROY_POST(p);
  36 }
  37
  38 static void sem_wait(sem_t *p)
  39 {
  40   unsigned old, new;
  41   struct timespec ts = { 0, 0 };
  42
  43   ANNOTATE_SEM_WAIT_PRE(p);
  44   do {
  45     old = p->value;
  46     new = old - 1;
  47     nanosleep(&ts, NULL);
  48     ts.tv_nsec = 1;
  49   } while (!old || !__sync_bool_compare_and_swap(&p->value, old, new));
  50   ANNOTATE_SEM_WAIT_POST(p);
  51 }
  52
  53 static void sem_post(sem_t *p)
  54 {
  55   ANNOTATE_SEM_POST_PRE(p);
  56   __sync_fetch_and_add(&p->value, 1);
  57 }
  58
  59 static void *thread_func(void *arg)
  60 {
  61   unsigned int i;
  62   unsigned int sum = 0;
  63
  64   for (i = 0; i < ITERATIONS; i++) {
  65     sem_wait(&s_sem);
  66     sum += s_counter;
  67     sem_post(&s_sem);
  68
  69     sem_wait(&s_sem);
  70     s_counter++;
  71     sem_post(&s_sem);
  72   }
  73
  74   return 0;
  75 }
  76
  77 int main(int argc, const char *argv[])
  78 {
  79   pthread_t tid[THREADS];
  80   unsigned int i;
  81
  82   sem_init(&s_sem, 1);
  83   for (i = 0; i < THREADS; i++)
  84     pthread_create(&tid[i], 0, thread_func, 0);
  85
  86   for (i = 0; i < THREADS; i++)
  87     pthread_join(tid[i], 0);
  88
  89   assert(s_counter == THREADS * ITERATIONS);
  90   assert(s_sem.value == 1);
  91   sem_destroy(&s_sem);
  92
  93   fprintf(stderr, "Finished.\n");
  94
  95   return 0;
  96 }